Radiotransformer



Patented Dec. 25, i928.

UNlTED STATES PATENT OFFICE,

FRANK D. PEARNE, OF CEIGAGO, ILLNGES; MARTHA K, PEARNE EXECUTRIX OF SAID FRANK D. PEARNE, DECESED.

RADIOTRANSFORMER.

Application filed March 16, 1925. Serial No. 15,965.

This invention relates mainly to radio receiving sets and more especially to amplifying transformers and accessories adapted for use in audio-current circuits.

The main objects of the invention are to provide an improved form of means for amplifying weak alternating currents, including especially Asuch currents ywhich are of audio frequency; to provide an improved form of transformer device adapted for use in or in connection with radio receiving sets; to provide an audio-transformer of improved form adapted to provide greater amplication than the ordinary ork xed reluctance form of sound current transformer, or the form having a substantially un- 'variable permanent field; to provide a multipleX regenerative transformer of improved form and characteristics for the purpose stated; to provide an improved form of transformer adapted for automatic variable reluctance in operation; to provide such a transformer having dynamo-electric action; and to provide in combination therewith a sensitive pressure rheostat attachment adapted and arranged to supplement the inductive action of the primary winding. Y

Several illustrative embodiments of this invention are shown by the accompanying drawings, in which:

Fig. l is a schematic diagram of a simple crystal receiving set, with one embodiment of the improved transformer devicein the audio circuit.

Fig. 2 is a similar view somewhat elaborated with a modied form of circuit connections including a three coil induction device besides the main transformer equipment in the audio circuit.

Fig. 3 is a diagram of a two tube receiving set with one embodiment of the transformer operably interposed between the tubes.

Fig. et is mainly a side elevation of a simple form of transformer such as represented in the diagram of Fig. l.

Fig. 5 is a side elevation of a modified form of transformer in which the essential parts ofthe movable member are` duplicated andarranged symmetrically about a central transverse pivotal axis, relative to which the stationary member is also symmetrically disposed.

Fig. 6 is a fragmentary view of a further modification of the transformer showing the vibratory armature part formed with four core arms in spider-like arrangment with coil spools thereon, instead of one arm and one spool or two arms and two spools, as represented by the two preceding figures, respectively, the view being substantially as taken on a horizontal section line such as at 6`6 on Fig. 5, the terminal plate being removed. A

Fig. 7 is a fragmentary horizontal sectional view of the device of Fig. 6, substantially as on a section line at 7--7 on Fig. 5.

Fig. 8 is merely a diagram of connections for the coils on the four pole vibrator of Fig. 6.

Fig. 9 merely illustrates the idea that the coil or coils may be carried by the stationary yoke instead of by the vibratory armature of a transformer substantially such as shown by Figs. l to 4.

Fig. 10 shows an embodiment wherein the magnetic pull tending to minimize the air gap is opposed. by gravity.

Fig. 1l shows an embodiment wherein the magnetic pull tending to minimize the air gap is opposed by the resilience of a singlepiece magnetic circuit core element.

Referring to the drawings, a very simple embodiment of this invention is shown by the crystal detector receiving circuit diagram of Fig. l. Here the aerial is connected to the ground G through an inductance I and a variable condenser C in parallel therewith, as usual, and the crystal detector C. D. is connected in series with the primary winding A on the vibratory armature 1 of the transformer 2, between thel aerial and ground. Said armature is provided with a secondary winding B leading to a loud speaker L. S., whereby the sounds transmitted to the primary winding are amplified by a single step-up transformer action. This action is augmented by the coincident variations in the air gap 3 and consequent reluctance changes.

In order to further amplify the sound currents, a tertiary winding C is connected in series with a variable pressure rheostat 4 and a battery 5. The vibratory responsiveness of the device and variation of the air gap are attained by providing for relative movement of the poles N and S according to variations in iux from the normal. In this instance the armature member l is pivoted to the yoke Y at Y and is urged, against va variable condenser the magnetic pull, to swing the pole N away from pole S, so as to enlarge the gap 3, for which purpose a spring l is adjustably set by a screw l according to speciiic needs.

Referring to Fig. 2, the equipment and connections are like those oic Fig. l, except that a second transformer or induction `coil T is interposed between the windings on armature l and loud speaker. Here the transformer T has two primaries, 6 and T, one of which is connected to the secondc Y winding B of Iarmature A and the other is connected to the circuit of the tertiary winding C, the secondary oi" transformer T being `connected directlyy to the loud speaker.

In order to show how this invention may be used in a tube set, reference is had te Fig. 3. Here the apparatus at the lett ot' transformer 2 is all connected in alcoidaiice with the usual or any well known practice, including preferably a vario coupler V. C., C and the vfirst tube or detector 8. Here the audio transformer circuit, including the plate P and Vfilament F of the iirst tube 8 and the B-ba-ttery, lis connected in series with the primary winding A yof the transformer 2.' The secondary winding B Vof said transformer is connected to the grid circuit of the second tube 9. The tertiary winding C is connected directly across the A battery, with the pressure rlieostat 4 and control switch l() in series. From the foregoing, in view ot the connections shown in Fig. 3, the operation of' the second tube in Venergizing the loud sneaker will be apparent. Here we have the directL step-up transformer action between the primary land secondary coils A. and B. The dynamo-electric eiiect oi' the primary winding in actuating the vibrator l strengthens the step-up edect. This eiiect is still turtlier supplemented by the tertiary windingtube 9 with corresponding results on the plate circuit thereof which` leads to the loud speaker.

` Referring next to the matter oi specific forms oic structure and design 'for the transformer and its accessories, attention directed to Fios. l to l1 illustrating a nuirber of di'iierent embodiments, each embo 7ving the main generic ideas characterEen@V this invention, and each having also p cilliar merits respectively according to various speciiic requirements. Y

The equipment shown in Fig. 4 is sin to that shown in the right hand para;

' tertiary, the

Fig. l, but includes more mechanical detail. Here the yoke Y is represented mounted on an insulating base l2 and the spring 13 for adjusting the position of the armature is mounted ot the iree end a thereof where it is held between?.

i oy a bracket li' adjusting screws l5 cL mounted on the upper t et 'the yoke Y. The pressure `ilieostat l includes a carbon button e or the like stationarily mounted 7F on support fr', and a s ing l cai the armature with its conta tip bWL i on said button. The wiring shown in connection with this ligure is diagrammatic and is believed to be selic explanatory.

eiierring new to a more elaborate si.- bodiment oi" the tra lol-shaped yoke 20,

lbearing 24e carried by an inverted lol-bracket 25, the ends or" which are secured by means 26 to the polar ends of the yoke. The pressure rlieostat 28 is positioned below the armature and the movable contact Q9 is carried by the said pivot shalt 22 in etlective relation to a stationary contact 30, as will be apparent from Fig. 7. i angular displacement ot the 'armature is adlief justable by means vet a screw 32V ca an insulated arm 38 on one arm oli fl vyo .-.a and arranged to coact with one end ot the leverage spring Sii carried by 'the pivot 't 22, on the opposite end of which sprin movable contact 29 of rlieostat 28 is nio ed. The said screw, which is arr-a be in tension, adjusted to sjaine ne armature 2l somewhat out aliiiement with the respective yoke poles, so at when an alternating current is applied to the former the armature will be caused brate accordingly, thereby Valso oner the pressure i'lieostat render Ane winding eiective.

The essential connections for this embodiment are substantially like those l and l except that the coils are alldu cated, one set being mounted on each a of the armature and the corresponding coils being connected in series and wire to a terminal block 36, as will be apparent.

A still further elaborated embodiment shown by 6, in which the Tvibrato armature l0 has four arms eil, instead ci. two, and on each arm is provided a coniplete set or" coils, primary, secondary and corresponding coils being connected in series, as in TEigs. Sand 8. The yoke 45 is here shown in circular shape,

J. 1 tei tiaiy ythevends of which are secured to a pair the plane of which is parallel with the plane of the spider-shaped armature, and four pole pieces 46 are provided thereon corresponding with thepoles of the armature. The armature is carried by4 an upright pivot 48, the ends of which are seated in insulated bearings, such as 23 and `4. The lower bearing is attached to the middle of a cross bar 5l shown fragmentarily in Fig. G. The upper bearing is attached to the middle of a cross bar r bracket, such as shown at 25 on Fig. 5, of opposite pole pieces, as indicated by the screw holes 53. The armature 40 as a whole is held normally somewhat deflected from the natural position of equilibrium which would be determined by the magnetic pull of the yoke poles 46, the means for accomplishinov this being substantially as shown lby Figs. 5 and 7, which appears to be quite apparent without further explanation. The circuit connections for the vari-V ous coils and equipment immediately related to the device in Fig. 6 may be visualized by reference to Fig. 8.

In some instances, as illustrated by Fig. 9, it is preferable to mount the coils on the yoke instead of on the armature, as in Fig. l. This arrangement diminishes the mass subject to vibration. In this view the pressure rheostat comprises a button member 4 carried by a bracket secured to one pole of the yoke Y and a contact spring 56 therefor is carried by the armature l, the working position of which is determined by the adjusting screw l acting on the spring l which is secured to the armature adjacent to its supporting pivot Y.

In the embodiment shown in Fig. 10, gravity operates in place of a spring to urge the armature l away from its natural position as would be determined by magnetic pull alone. An alternating` current acting on the primary winding P varies the flux and hence varies the pull on the armature, which accordinglyswings vibratingly up and down, thereby producing the desired supplementary effect on the secondary windings to which the loud speaker is connected.

Referring now to the very simple embodiment shown in Fig. 1l, the magnetic member is unitary in character and comprises a single bar 58 formed in a loop with the ends disposed adjacent to each other, but with the poles spaced apart slightly to provide an air gap 3 in the characteristic relation of the transformers herein shown. rIhe axes of these poles are displaced somewhat from mutual alinement and the magnetic pull tends to overcome the resilience of the magnetic pair and pull them into alinement. Hence, when an alternating current is applied to the primary coil P, one of the poles is caused to vibrate relative to the other in accordance with the frequency and intensity of the current impulses. Here the pressure rheostat comprises a button 60 attached to one pole in combination with a spring 61 attached to the other pole for coaction in a circuit including a battery 5 and a tertiary winding, whereby the effect on the secondary wind* ing is amplified.

The operation of my improved transformer, which is essentially electro-mechanical, is substantially the same in each of the several embodiments described. Multiple regeneration is provided for in each instance, either duplex or triplex. With this in view it will suflice to follow through the operation of that assemblage shown in Fig. 3.

lIVhen the filament F of tube 8 is energized current flows from the plate battery B through the primary coil A. This augments the flux in transformer 2 and causes the armature l to be drawn somewhat closer to the yoke Y against the yielding resistance of spring l and thus diminish the air gap 8. Then the changes in the plate current due to tube resistance changes occasioned by a signal or to intake energy on the grid G will cause corresponding vibratory yfluctuations in the transformer core flux and consequently will induce currents in the secondary coil B. Furthermore, the physical vibration of armature l operates to vary the pressure on rheostat 4 which controls the tertiary winding C, and this supplements coil A and so acts to augment the flux changes and secondaries passing to the sound reproducer, either loud speaker or head phones. The multiple regenerative factors of the transformer may be defined broadly as (l) simple inductive, static, between the primary and secondary windings, (2) dynamo-electric, between said windings, due to mechanical action of the core element or elements, and (3) tertiary, between a rheostat controlled undulatory current winding and the said secondary.

Although several specific embodiments of this invention have been herein shown and described, it is to be understood that no attempt has been made to show or specifically describe all practical embodiments and that some of the details of the constructions shown and described may be altered or amended without departing from the spirit of the invention as defined by lthe following claims.

I claim:

l. A sound amplifying transformer comprising a magnet having windings thereon adapted and arranged to provide a pair of mutually inductive electrical circuits, said magnet including a pair of relatively movable core parts included in the magnetic circuit and arranged to provide by their reta-r said resilient means being adjustable.

2. In a device of the character described,

a transformer comprising a permanent mag-4 net mounted stationarily in combination with a vibratoiily mounted armature substantially bridging the space between the poles or' said magnet, but With a slight variable air gap at one end of said armature, resilient means urging said armature away from its natural position of equilibrium, one of the magnetic members having thereon a primary winding and a secondary winding inductively related thereto.

3. In a device of the character described, a. transformer comprising a. pair of core members pivotal-ly connected at one point and arranged to provide a small variable air gap when they swing to their normal position of magnetic equilibrium, resilient means urging said members apart t0 increase said air gap and imrtually inductive windings operatively relatedk to the magnetic circuit of said transformer.

4;. A transformer comprising open circuit core means having a variable air gap and windings inductively related to said core means, said means being normally disposed in maximumV gap conformity and being electromagnetically responsive to one of said windings to minimize said gap.

Signed 'at Chicago this 14th day of 1925-.

March,

FRANK D. PEARNE. 

